Hourly integrated concentrations of plasma melatonin and LH are measured for 24h in normal children, adolescents, and in patients with disorders of growth and/or sexual maturation. The response of LH and FSH to LHRH is also determined. Circadian rhythms of melatonin and LH will be compared among groups of children of either sex different stages of puberty and according to LH response to LHRH.